1. Field of Invention
The present invention relates to technical fields of electrooptic devices and electronic devices. More particularly, the invention relates to technical fields of an electrooptic device having various capacitors in which charges are accumulated, a driving method therefor, an electronic device, and a projection display device.
2. Description of Related Art
Currently, electrooptic devices are known which can be driven by a so-called active matrix driving method by having pixel electrodes arranged in a matrix, thin film transistors (TFT) connected to the pixel electrodes, scanning lines and data lines provided in parallel in rows and columns, and the like. Such electrooptic devices can further include a TFT array substrate on which the TFTs, the pixel electrodes, and the like described above are formed, a counter substrate opposing the TFT array substrate and having a common electrode, and an electrooptic substance, such as liquid crystal, sandwiched between the TFT array substrate and the counter substrate (liquid crystal). By supplying a driving voltage, a driving signal, an image signal, and the like to a scanning-line driving circuit and a data-line driving circuit that are connected to the scanning lines and the data lines, a predetermined electric field is applied to the liquid crystal through the pixel electrodes, and the light transmittance ratio is changed in each pixel by the resulting state change of the liquid crystal, so that an image can be displayed.
However, conventional electrooptic devices have the following problem. While a driving voltage, a driving signal, an image signal, and the like are necessary to drive an electrooptic device, as described above, no special consideration is given to a way to turn off these various signals when the device is powered off. Therefore, irregular charges inevitably remain everywhere inside the electrooptic device during operation of the electrooptic device.
In a state in which such charges remain inside the electrooptic device, when the device is powered on again, an image resulting from the charges sometimes appears on an image. For example, in a case in which letters “ABC” are displayed on an image immediately before the device is powered off, when the device is powered on next, the letters “ABC” in the preceding use appear like afterimages.
Incidentally, it was first considered that charges remained in capacitors (so-called “liquid crystal capacitors”) formed by the TFT array substrate, the liquid crystal, and the counter substrate described above. In a case in which the electrooptic device has storage capacitors, the above-described problem tends to be more pronounced. The storage capacitors are capacitors that improve the potential holding characteristics of pixel electrode and enhance image quality by holding a voltage applied to the pixel electrodes for a predetermined period until the next image signal is applied to the pixel electrodes. However, such provision of storage capacitors is equal to the addition of new places in which charges are accumulated inside the electrooptic device, and the above problem appears more pronouncedly.
In addition, in recent electrooptic devices, the cell gap between the TFT array substrate and the counter substrate is further reduced, and the structure of the storage capacitors is complicated in order to achieve size reduction and high definition. Consequently, it is more difficult to remove accumulated charges, and there is a greater fear that the above problem will arise.